Pete,
Do you know the name of the person that tried to provide you with some enlightenment.
What he is saying is possible. It all comes down to the skill of the builder.
So there would be some people who can do this and many more people who could not.
I know some people who built timber A classes 20 yrs ago and they came out at 74kg. Up until a couple of years ago I knew where two of the three were still sailing. I'm aware of No problems other than a crack in the front beam of one of them after more than 10 yrs. No big deal the round aluminium tube was replaced.

Since then with hull shape changes moving the bouyancy lower in the hulls there has been a decrease in the required surface area of the hulls which would normally amount to decrease in weight of the hulls. This is partly why they are now building composite As up to 5kg under min.

So IF you are skilled enough and IF you have a shape that can be easily formed from ply there are people who could do this.

When you say the old boats were heavy or that they broke I put it to you that these boats were built by those who could not do this.

As for the statement As don't last because you don't see the older ones around.
I think this has a lot more to do with the specialist use of these boats. They are not designed as recreational boats and as the hull shapes of the boats at the front of the fleet have evolved so much the older boats no longer are of any use.

Just the way I see it.

Regards,
Phill